挤压膨化过程中物料组分的变化分析

Changes of Material Components during Extrusion

挤压膨化加工广泛应用于食品加工业。挤压膨化过程中,物料组分发生了复杂的物化变化。在高温、高压、高剪切力环境下,淀粉分子间的氢键断裂,淀粉发生糊化、降解,生成小分子量物质,淀粉水溶性增强;蛋白质发生变性、重组,发生组织化,蛋白质水溶性和生物学效价下降;脂肪与淀粉以及蛋白质形成脂肪复合体,淀粉溶解性和消化率降低,脂肪氧化速度减慢,氧化程度减小,产品货架期延长。

Extrusion is widely used in food processing industry. During extrusion processing, complex physicochemical changes take place in material components. Under the conditions of high temperature, high pressure and high shear forces, the hydrogen bonds among starch molecules are disrupted; gelatinization and degradation of starch occur. Mean while, lower molecular weight material forms and solubility of starch increases. On the other hand, proteins are denatured and recombined, which result in decrease of water solubility and biological value of proteins. The interactions of lipids, starch and proteins lead to formation of lipid compound. Solubility and digestive rate of starch will decrease; lipids oxidation rate will slow down; and the degree of lipids oxidation will decrease. Consequently, the shelf life of product will be extended.